Adds example to locals() docstring.
Adds docstring to rstgen.defaultConfig.
Remove assert in asyncio which causes problems.

This assert keeps failing occassionally in nimbuild causing it to crash.
According to logic it shouldn't, but perhaps the socket's writeable
status changes.
Fixes #594

This was already partially fixed, ``expandTilde`` was the missing piece
from perfection.
Merge pull request #776 from gradha/pr_docs

Docstrings